He passed through a difficult period _____ after his marriage broke down. 

The H1N1 flu spread very quickly at the beginning, __________, many people were ill.

This question is ______ easy, all the students can answer the question.

 Furniture and flooring usually come to mind when we think of ways to use bamboo. Not many of us, ________, think of bamboo clothing.

 If you haven’t had enough sleep, your actions will give you _____ during the day.